1. Field of the Invention
This invention relates to the field of bone fracture fixation utilizing compression plates. More particularly, it relates to a method of fracture fixation in which cerclage wiring is used in conjunction with bone plates.
2. Description of the Prior Art
In the past, many types of bone plates have been applied to bones, some by screws and others with the help of wire loops. These plates may be of any size or shape, but are usually L-shaped or straight. These plates are placed on the tension side of the non-union (convex side) with the compression plate acting as a tension band which provides dynamic rather than static compression. In the last 20 years bone plates having a self-compressing effect caused by eccentric screw placement was combined with the gliding or sliding effect between the screw head and the plate hole to allow for a greater force transmission within the bone during weight bearing period. Furthermore, due to the spherical configuration of both screw heads and plate holes, the compression instituted initially, is maintained throughout the healing process, even if the screws are not placed at right angles to the plate.
It has also been well known to use wires or cables such as Kirschner wires to fix fractures. Cerclage wiring techniques have been used for fixing long bone fractures, usually in combination with other fixation devices such as bone plates. The wires are passed at a 90.degree. angle to the long axis of the bone in an attempt to prevent slipping in a longitudinal direction and hence loosening.
It is also known in the prior art that when fractures of the femur occur after a prosthetic implant is implanted, that a combination of the use of a bone plate including bone screws in the distal section of a fractured femur may be utilized, but such screws cannot be easily utilized in the proximal section of the fractured femur due to the stem of the implanted, for example, femoral prosthesis. Clearly, for fractures in which the entire medullary canal is filled with a prosthetic stem with or without bone cement, placement of a new internal pin or a new prosthesis with a longer stem is not a viable means of intramedullary fixation.
An alternate method has been used to fix the fracture in which a bone plate is secured by cortical screws in the femur distal to the prosthesis and to secure the plate proximally with the use of cerclage wires. In the past this has required the use of a special bone plate. It is in this situation that the wire or cable positioning insert of the present invention is intended to be used. It has been found that the cerclage wiring around the bone plate tends to migrate longitudinally and can also migrate circumferentially about the bone even after the ends of the wire are clipped together using a standard trochanteric cable crimp sleeve.
By use of the present invention, cerclage wire or cable may be positioned with respect to any desired hole in a bone plate with the positioning insert also acting as a crimp sleeve so that once the wire has been crimped to the positioning insert, longitudinal and circumferential movement is prevented.
In addition, the insert is sized to fit partially within the screw apertures of standard bone plates so that the special bone plates of the prior art are unnecessary.